Xray-core/app/dns/dohdns.go

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package dns
import (
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"sync"
"sync/atomic"
"time"
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"github.com/xtls/xray-core/common"
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"github.com/xtls/xray-core/common/log"
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"github.com/xtls/xray-core/common/net"
"github.com/xtls/xray-core/common/net/cnc"
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"github.com/xtls/xray-core/common/protocol/dns"
"github.com/xtls/xray-core/common/session"
"github.com/xtls/xray-core/common/signal/pubsub"
"github.com/xtls/xray-core/common/task"
dns_feature "github.com/xtls/xray-core/features/dns"
"github.com/xtls/xray-core/features/routing"
"github.com/xtls/xray-core/transport/internet"
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"golang.org/x/net/dns/dnsmessage"
)
// DoHNameServer implemented DNS over HTTPS (RFC8484) Wire Format,
// which is compatible with traditional dns over udp(RFC1035),
// thus most of the DOH implementation is copied from udpns.go
type DoHNameServer struct {
dispatcher routing.Dispatcher
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sync.RWMutex
ips map[string]record
pub *pubsub.Service
cleanup *task.Periodic
reqID uint32
clientIP net.IP
httpClient *http.Client
dohURL string
name string
}
// NewDoHNameServer creates DOH client object for remote resolving
func NewDoHNameServer(url *url.URL, dispatcher routing.Dispatcher, clientIP net.IP) (*DoHNameServer, error) {
newError("DNS: created Remote DOH client for ", url.String()).AtInfo().WriteToLog()
s := baseDOHNameServer(url, "DOH", clientIP)
s.dispatcher = dispatcher
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tr := &http.Transport{
MaxIdleConns: 30,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 30 * time.Second,
ForceAttemptHTTP2: true,
DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
dispatcherCtx := context.Background()
dest, err := net.ParseDestination(network + ":" + addr)
if err != nil {
return nil, err
}
dispatcherCtx = session.ContextWithContent(dispatcherCtx, session.ContentFromContext(ctx))
dispatcherCtx = session.ContextWithInbound(dispatcherCtx, session.InboundFromContext(ctx))
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dispatcherCtx = log.ContextWithAccessMessage(dispatcherCtx, &log.AccessMessage{
From: "DoH",
To: s.dohURL,
Status: log.AccessAccepted,
Reason: "",
})
link, err := s.dispatcher.Dispatch(dispatcherCtx, dest)
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
}
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if err != nil {
return nil, err
}
cc := common.ChainedClosable{}
if cw, ok := link.Writer.(common.Closable); ok {
cc = append(cc, cw)
}
if cr, ok := link.Reader.(common.Closable); ok {
cc = append(cc, cr)
}
return cnc.NewConnection(
cnc.ConnectionInputMulti(link.Writer),
cnc.ConnectionOutputMulti(link.Reader),
cnc.ConnectionOnClose(cc),
), nil
},
}
s.httpClient = &http.Client{
Timeout: time.Second * 180,
Transport: tr,
}
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return s, nil
}
// NewDoHLocalNameServer creates DOH client object for local resolving
func NewDoHLocalNameServer(url *url.URL, clientIP net.IP) *DoHNameServer {
url.Scheme = "https"
s := baseDOHNameServer(url, "DOHL", clientIP)
tr := &http.Transport{
IdleConnTimeout: 90 * time.Second,
ForceAttemptHTTP2: true,
DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
dest, err := net.ParseDestination(network + ":" + addr)
if err != nil {
return nil, err
}
conn, err := internet.DialSystem(ctx, dest, nil)
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log.Record(&log.AccessMessage{
From: "DoH",
To: s.dohURL,
Status: log.AccessAccepted,
Detour: "local",
})
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if err != nil {
return nil, err
}
return conn, nil
},
}
s.httpClient = &http.Client{
Timeout: time.Second * 180,
Transport: tr,
}
newError("DNS: created Local DOH client for ", url.String()).AtInfo().WriteToLog()
return s
}
func baseDOHNameServer(url *url.URL, prefix string, clientIP net.IP) *DoHNameServer {
s := &DoHNameServer{
ips: make(map[string]record),
clientIP: clientIP,
pub: pubsub.NewService(),
name: prefix + "//" + url.Host,
dohURL: url.String(),
}
s.cleanup = &task.Periodic{
Interval: time.Minute,
Execute: s.Cleanup,
}
return s
}
// Name returns client name
func (s *DoHNameServer) Name() string {
return s.name
}
// Cleanup clears expired items from cache
func (s *DoHNameServer) Cleanup() error {
now := time.Now()
s.Lock()
defer s.Unlock()
if len(s.ips) == 0 {
return newError("nothing to do. stopping...")
}
for domain, record := range s.ips {
if record.A != nil && record.A.Expire.Before(now) {
record.A = nil
}
if record.AAAA != nil && record.AAAA.Expire.Before(now) {
record.AAAA = nil
}
if record.A == nil && record.AAAA == nil {
newError(s.name, " cleanup ", domain).AtDebug().WriteToLog()
delete(s.ips, domain)
} else {
s.ips[domain] = record
}
}
if len(s.ips) == 0 {
s.ips = make(map[string]record)
}
return nil
}
func (s *DoHNameServer) updateIP(req *dnsRequest, ipRec *IPRecord) {
elapsed := time.Since(req.start)
s.Lock()
rec := s.ips[req.domain]
updated := false
switch req.reqType {
case dnsmessage.TypeA:
if isNewer(rec.A, ipRec) {
rec.A = ipRec
updated = true
}
case dnsmessage.TypeAAAA:
addr := make([]net.Address, 0)
for _, ip := range ipRec.IP {
if len(ip.IP()) == net.IPv6len {
addr = append(addr, ip)
}
}
ipRec.IP = addr
if isNewer(rec.AAAA, ipRec) {
rec.AAAA = ipRec
updated = true
}
}
newError(s.name, " got answer: ", req.domain, " ", req.reqType, " -> ", ipRec.IP, " ", elapsed).AtInfo().WriteToLog()
if updated {
s.ips[req.domain] = rec
}
switch req.reqType {
case dnsmessage.TypeA:
s.pub.Publish(req.domain+"4", nil)
case dnsmessage.TypeAAAA:
s.pub.Publish(req.domain+"6", nil)
}
s.Unlock()
common.Must(s.cleanup.Start())
}
func (s *DoHNameServer) newReqID() uint16 {
return uint16(atomic.AddUint32(&s.reqID, 1))
}
func (s *DoHNameServer) sendQuery(ctx context.Context, domain string, option dns_feature.IPOption) {
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newError(s.name, " querying: ", domain).AtInfo().WriteToLog(session.ExportIDToError(ctx))
if s.name+"." == "DOH//"+domain {
newError(s.name, " tries to resolve itself! Use IP or set \"hosts\" instead.").AtError().WriteToLog(session.ExportIDToError(ctx))
return
}
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reqs := buildReqMsgs(domain, option, s.newReqID, genEDNS0Options(s.clientIP))
var deadline time.Time
if d, ok := ctx.Deadline(); ok {
deadline = d
} else {
deadline = time.Now().Add(time.Second * 5)
}
for _, req := range reqs {
go func(r *dnsRequest) {
// generate new context for each req, using same context
// may cause reqs all aborted if any one encounter an error
dnsCtx := context.Background()
// reserve internal dns server requested Inbound
if inbound := session.InboundFromContext(ctx); inbound != nil {
dnsCtx = session.ContextWithInbound(dnsCtx, inbound)
}
dnsCtx = session.ContextWithContent(dnsCtx, &session.Content{
Protocol: "https",
//SkipRoutePick: true,
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})
// forced to use mux for DOH
// dnsCtx = session.ContextWithMuxPrefered(dnsCtx, true)
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var cancel context.CancelFunc
dnsCtx, cancel = context.WithDeadline(dnsCtx, deadline)
defer cancel()
b, err := dns.PackMessage(r.msg)
if err != nil {
newError("failed to pack dns query for ", domain).Base(err).AtError().WriteToLog()
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return
}
resp, err := s.dohHTTPSContext(dnsCtx, b.Bytes())
if err != nil {
newError("failed to retrieve response for ", domain).Base(err).AtError().WriteToLog()
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return
}
rec, err := parseResponse(resp)
if err != nil {
newError("failed to handle DOH response for ", domain).Base(err).AtError().WriteToLog()
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return
}
s.updateIP(r, rec)
}(req)
}
}
func (s *DoHNameServer) dohHTTPSContext(ctx context.Context, b []byte) ([]byte, error) {
body := bytes.NewBuffer(b)
req, err := http.NewRequest("POST", s.dohURL, body)
if err != nil {
return nil, err
}
req.Header.Add("Accept", "application/dns-message")
req.Header.Add("Content-Type", "application/dns-message")
hc := s.httpClient
resp, err := hc.Do(req.WithContext(ctx))
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if err != nil {
return nil, err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
io.Copy(ioutil.Discard, resp.Body) // flush resp.Body so that the conn is reusable
return nil, fmt.Errorf("DOH server returned code %d", resp.StatusCode)
}
return ioutil.ReadAll(resp.Body)
}
func (s *DoHNameServer) findIPsForDomain(domain string, option dns_feature.IPOption) ([]net.IP, error) {
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s.RLock()
record, found := s.ips[domain]
s.RUnlock()
if !found {
return nil, errRecordNotFound
}
var ips []net.Address
var lastErr error
if option.IPv6Enable && record.AAAA != nil && record.AAAA.RCode == dnsmessage.RCodeSuccess {
aaaa, err := record.AAAA.getIPs()
if err != nil {
lastErr = err
}
ips = append(ips, aaaa...)
}
if option.IPv4Enable && record.A != nil && record.A.RCode == dnsmessage.RCodeSuccess {
a, err := record.A.getIPs()
if err != nil {
lastErr = err
}
ips = append(ips, a...)
}
if len(ips) > 0 {
return toNetIP(ips), nil
}
if lastErr != nil {
return nil, lastErr
}
if (option.IPv4Enable && record.A != nil) || (option.IPv6Enable && record.AAAA != nil) {
return nil, dns_feature.ErrEmptyResponse
}
return nil, errRecordNotFound
}
// QueryIP is called from dns.Server->queryIPTimeout
func (s *DoHNameServer) QueryIP(ctx context.Context, domain string, option dns_feature.IPOption) ([]net.IP, error) { // nolint: dupl
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fqdn := Fqdn(domain)
ips, err := s.findIPsForDomain(fqdn, option)
if err != errRecordNotFound {
newError(s.name, " cache HIT ", domain, " -> ", ips).Base(err).AtDebug().WriteToLog()
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log.Record(&log.DNSLog{s.name, domain, ips, log.DNSCacheHit, 0, err})
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return ips, err
}
// ipv4 and ipv6 belong to different subscription groups
var sub4, sub6 *pubsub.Subscriber
if option.IPv4Enable {
sub4 = s.pub.Subscribe(fqdn + "4")
defer sub4.Close()
}
if option.IPv6Enable {
sub6 = s.pub.Subscribe(fqdn + "6")
defer sub6.Close()
}
done := make(chan interface{})
go func() {
if sub4 != nil {
select {
case <-sub4.Wait():
case <-ctx.Done():
}
}
if sub6 != nil {
select {
case <-sub6.Wait():
case <-ctx.Done():
}
}
close(done)
}()
s.sendQuery(ctx, fqdn, option)
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start := time.Now()
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for {
ips, err := s.findIPsForDomain(fqdn, option)
if err != errRecordNotFound {
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log.Record(&log.DNSLog{s.name, domain, ips, log.DNSQueried, time.Since(start), err})
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return ips, err
}
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-done:
}
}
}